1. Field of the Invention
The present invention relates to a sheet feeding apparatus for automatically supplying recording sheets to a recording station of a recording system one by one.
2. Related Background Art
Recording systems such as printers, copying machines, facsimiles and the like are so designed that an image consisting of a dot pattern is formed on a recording sheet such as a paper, plastic film and the like by energizing energy generating bodies of a recording head in response to image information sent to the system.
Such recording systems can be grouped into ink jet recording systems wire dot recording systems thermal recording systems laser beam recording systems and the like, in accordance with a recording principle.
Further, the recording sheets used with the recording system include a thicker sheet such as a post card, envelope, and a special sheet such as a plastic film, other than a plain paper. The recording sheets can be manually supplied one by one or automatically and continuously supplied by an automatic sheet supplying apparatus.
The automatic sheet supplying apparatus generally comprises a sheet supply drive portion for feeding a recording sheet by rotating a sheet supply roller, and a sheet supply cassette portion in which the recording sheets are stacked. By driving the sheet supply roller by a driving force from a recording sheet feeding mechanism of the recording system, the sheets are separated and supplied one by one.
Further, the automatic sheet supplying apparatus can be grouped into an integrated type wherein the apparatus is incorporated into the recording system and a removable type wherein the apparatus is removably mounted on the recording system. The present invention can be applied to both types. In addition, the automatic sheet supplying apparatus of this kind is also provided with a sheet path surface for guiding the sheet supplied from the sheet supply cassette to the recording station.
The sheet path surface sometimes acts as a manual sheet supply surface, too. Further, the sheet path surface is normally inclined with respect to an advancing direction of the sheet supplied from the sheet supply cassette, so as to make the apparatus compact. The inclined angle of the sheet path surface is sometimes relatively great (for example, about 60 degrees) for the compactness of the apparatus.
With this arrangement, when a guide for guiding the sheet is arranged at a junction between a sheet path for the automatic sheet supply and a sheet path for the manual sheet supply, since the automatically supplied sheet is bent by the guide, the friction between the guide and the sheet is increased, thus increasing the back tension to the sheet (resistance in the sheet feeding direction). Consequently, the feeding of the sheet is unstable, resulting in a discrepancy in the image on the sheet at the recording station, thus reducing the image quality.